Docs: Minor updates to the Environment variables docs

[jonniebigodes]

With this pull request, the Environment variables documentation was updated to factor in some information about Vite and how to obtain environment variables specific to this builder.

What was done:

• Minor wording tweaks
• Consolidated the snippets to become framework agnostic to reduce the maintenance cost
• Introduced conditional rendering of the documentation to avoid confusion

Closes #23528

@IanVS, when you have a moment, can you take a look and let me know of any feedback you have? Appreciate it

How to test

1. Follow the steps in the contributing instructions for this branch, chore_env_vars_tweaks.

2. Open the relevant documentation, and for Vite frameworks, you should see a similar section added to the documentation

Checklist

• Make sure your changes are tested (stories and/or unit, integration, or end-to-end tests)
• Make sure to add/update documentation regarding your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli/src/sandbox-templates.ts
• Make sure this PR contains one of the labels below.

["cleanup", "BREAKING CHANGE", "feature request", "bug", "build", "documentation", "maintenance", "dependencies", "other"]

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core team members can create a canary release here or locally with gh workflow run --repo storybookjs/storybook canary-release-pr.yml --field pr=<PR_NUMBER>

[IanVS]

Storybook and your framework may have specific configurations and may not be able to recognize and use those environment variables.

This is where envPrefix can be used, right? Is that worth mentioning here instead of making it seem like there is no solution?

[jonniebigodes]

That's a great catch, and we can pivot the documentation toward it and provide a workaround for this for now. I'll update it shortly.

[jonniebigodes]

@IanVS just updated this based on your suggestion. Let me know, and we'll go from there.

[IanVS]

Thanks, I think this is good. For some reason I thought that envPrefix was a storybook option, but you're right it's in Vite. I believe we do read that option though when deciding which env variables to expose to stories. So, ideally environment variables should "just work" from Storybook's perspective. But doesn't hurt to point it out and give folks the option to contact us if something wonky is happening.

[jonniebigodes]

No problem. Appreciate you taking the time to review it and point me in that direction 🙇 .

[IanVS]

Looks good to me, thanks for the updates!

[kylegach]

Thanks for these updates! I'm good with merging this as-is for now, but we should consider restructuring this page to divide it into process.env and import.meta.env sections.

[jonniebigodes]

I'm aware of this, I just wanted to get the information in for now, so that we flush it out later on in more detail later on.